1. Field of the Invention
The present invention is in the field of agricultural equipment and consists of a wagon that, when pulled by a tractor along one or more plant beds, loosens a buried or unburied drip tape from the soil, removes air and water from the drip tape, and winds the drip tape onto a reel for reuse or disposal.
2. The Prior Art
The type of drip irrigation tubing with which the present invention is concerned is a flexible tubular conduit of polyethylene plastic. It is available in wall thicknesses ranging from 4 to 15 mils, and is usually sold in reels that contain 6000 to 15,000 feet depending on the wall thickness. The tape has a circumference of 2.0 inches, so that when flattened it has a width of 1 inch. Tiny apertures spaced eight inches apart or more along the length of the tape permit pressurized water to drip from the conduit at a slow and predetermined rate.
Although a few users of the drip tape are content to leave it lying on the surface of the plant bed, most users prefer to bury the drip tape at depths of several inches. For a typical plant bed spacing, approximately 13,800 feet of drip tape are required to irrigate one acre. Since a large producer may have a 1,000 acres, it can be seen that millions of feet of drip tape will be involved.
Drip tape irrigation is routinely used in the production of celery, lettuce, broccoli, and cauliflower. Typically, these crops are planted on elevated beds that are approximately 22 inches across and that are approximately 38 inches from center-to-center. For celery, lettuce, and broccoli, normally two lines of plants are located near opposite sides of the bed. Usually a single line at the center of the bed is used for cauliflower. After the raised beds have been formed, the drip tape is buried at the center of the bed and the plants are then planted. The drip tape remains in place until the crop is harvested. After the harvest, the tape must be removed because it would be thrown out of position and damaged by subsequent cultivation of the soil. Thus, in locations where two or three crops per year are grown, the drip tape must be put in place and then removed as many times.
Prior to the present invention, it was common practice for a crew of workers to manually pull the drip tape from the soil and to roll it into loose bundles which were then loaded onto a vehicle and taken to a depot for disposal. Thus, each year many millions of feet of used drip tape were disposed of at a considerable cost that included both the cost of removing the tape from the soil and the cost of disposing of the removed tape. The used tape was considered to be unreusable, partly because of the manner in which it was bundled up.
The present invention overcomes this wasteful practice by permitting the recycling of drip tape, and in the process greatly lowers the cost of removing the drip tape from the soil.
In U.S. Pat. No. 4,447,173 issued May 8, 1984, Schultz et al. describe an apparatus useful for burying drip tape, but it is clear that the same apparatus cannot be used in reverse to remove the drip tape from the soil.
In French Patent No. 2,399,796 to Budzyn, published 9 March 1979, there is described a tractor attachment usable for rolling up an elongated sheet of plastic such as used in horticulture. The vehicle includes a blade that is continuously pushed forward under the plastic sheet to pick up the sheet, which is then wound onto a drum that is turned by the ground-contacting wheels.
In U.S. Pat. No. 4,796,711 issued Jan. 10, 1989, Chrysler describes a similar apparatus for removing sheets of plastic film from raised plant beds.
The problem solved by Budzyn and by Chrysler is in some ways simpler than that which faced the present inventor. For example, the sheet of plastic film recovered by the apparatus of Budzyn or of Chrysler is not buried beneath several inches of soil, although some soil is used at the lateral edges to prevent the wind from picking up the film. Also, the sheet of plastic recovered by the apparatus of Budzyn or of Chrysler consists of a single layer and thus does not contain water or air, both of which complicate the recovery of drip tape.
In U.S. Pat. No. 3,866,532 issued Feb. 18, 1975, Ogden, Jr. describes a firehose retractor for removing trapped water and air from firehoses. The firehose is drawn through a wringer which also includes brushes that remove small stones and other debris from the outside of the firehose. Although the firehose retractor could, conceivably, be used while the fire engine is in motion, there is no provision for matching the speed of the rollers of the wringer with the groundspeed of the fire engine. This aspect of the problem is dealt with in a different and simpler manner in the present invention.
Thus, the prior art does not disclose an apparatus that could be used to solve the problem which the present inventor set out to solve, namely, to recover buried drip tape from the soil and to wind it onto reels in a smooth manner so that the plastic drip tape can be reused.